Iburg is a ruined hill castle in Westphalia. It was build around the 8th century, dating back to the time of Charlemagne and his war with the Saxons. Today it is a popular day-trip destination and the tower, named after Charlemagne (Kaiser Karl Turm), can be climbed for beautiful views.
It is likely that the castle was originally erected by Saxons as a fortified stronghold but once conquered Charlemagne build a chapel within its confines to honour St.Peter, which he eventually gifted to the Arch-Diocese of Paderborn. From 1134 a monastery briefly used the castle before the Bishop of Paderborn fortified it to become a stronger military fortress in the late 12th century. The Iburg never saw much action, however, and slipped from importance until the 15th century, when Otto of Braunschweig destroyed it. The castle was not restored and the close-by city of Bad Driburg inherited the holdings.
First archeological surveys were undertaken on 1900 and gradually the ruins where freed and restored to serve as tourist attraction.
References:The Château du Lude is one of the many great châteaux of the Loire Valley in France. Le Lude is the most northerly château of the Loire Valley and one of the last important historic castles in France, still inhabited by the same family for the last 260 years. The château is testimony to four centuries of French architecture, as a stronghold transformed into an elegant house during the Renaissance and the 18th century. The monument is located in the valley of Le Loir. Its gardens have evolved throughout the centuries.